Agronomic Services — News Release

Agronomic consulting service available from NCDA&CS

Billy Wood (left) of Franklin County confers with regional agronomist Charles Mitchell about the progress of his new greenhouse tomato production system.

CASTALIA—North Carolina provides many resources to its farmers. One that is unique to the state is the agronomic testing and consulting service offered through the N.C. Department of Agriculture and Consumer Services.

Thirteen regional agronomists within the Agronomic Division’s field services section help growers manage all types of crop-nutrient issues. "They make site visits, provide advice on lime and fertilizer application, demonstrate sampling techniques and help growers troubleshoot and manage potential nutrient problems," said Agriculture Commissioner Steve Troxler.

Billy Wood, who raises a variety of fruit and vegetable crops in Franklin County, is sold on the service. “ It’s free help,” he said. “Every grower can use that.”

NCDA&CS regional agronomists focus on providing advice about crop nutrition. They promote the awareness and appropriate use of Agronomic Division services, such as soil testing, plant tissue analysis, waste analysis and solution analysis. They also help identify nematodes —which are microscopic, plant-parasitic worms—because these pests usually produce root damage and are often the cause of crop-nutrient deficiencies.

Wood is particularly pleased with the help he received during the past year from his regional agronomist, Charles Mitchell. Wood had been noticing a decline in the quality of his greenhouse tomatoes over several seasons, but last spring, many of his plants actually died. When Mitchell visited the site, he suspected a nematode problem. To confirm his suspicions and rule out any other possible problems, he collected samples for soil nutrient analysis, nematode assay and water quality.

Test results revealed a dual problem: excessively high populations of root-knot nematodes along with unusually high levels of copper and zinc. Both problems had been building up over time due to the fact that Wood was accustomed to planting his greenhouse tomatoes in the soil and fertilizing them with poultry litter. Continuous growth of the same crop in the same soil led to high nematode populations and an accumulation of fertilizer salts.

To deal with the problem, Mitchell suggested that Wood stop growing tomatoes in the ground. Mitchell took him to visit three different greenhouse operations where tomatoes were being successfully grown in plastic bags filled with commercial planting media. Wood was impressed and decided to make the change.

“The idea of growing tomatoes in bags and regulating the application of fertilizer through a drip system was appealing,” says Wood. “It seemed more controlled—like driving with a speedometer versus not.”

Mitchell showed him how to set up the fertilizer/irrigation system, use solution analysis to check the quality of the source water and, later, double-check the nutrient concentration in the solution. The system Wood settled on has two separate tanks: one for the nitrogen solution and the other for the rest of the nutrients. However, instead of alternating days of application, as some growers do, Wood has his system set up so that both solutions inject simultaneously.

“Growing tomatoes in bags is simpler than growing them in the ground,” says Wood. “Once you get the pattern established, everything is routine.”

Wood, who has been growing greenhouse tomatoes for about ten years, is convinced that his new system is not only producing higher quality tomatoes but also a lot more of them, maybe twice as many. Next year he plans to try growing cucumbers the same way.

Greenhouse crops are typically high-value commodities that require significant investments. Mitchell has shown Wood that routine agronomic testing can help protect these investments. A good annual program includes a preseason test of source water quality as well as an early-season test to verify that all nutrient solutions are reaching the expected target concentration. Growers who want to monitor crop nutrition should tissue sample biweekly beginning at least two weeks before flowering.

The NCDA&CS Field Services section has been helping N.C. growers manage fertilization and other nutrient-related issues for nearly 30 years. Contact information for the service’s regional agronomists is located online atwww.ncagr.com/agronomi/rahome.htm or by calling (919) 733-2655.